Phase behavior of blends of linear low density polyethylene and poly(ethene-propene-l-butene)

The aim of this work was the study of blends of linear low density polyethylene (LLDPE) and an ethene-propene-l-butene terpolymer (t-PP). Two types of polyethylene were used to prepare the blends: an ethene-co-l-hexene (LLDPE(H)) copolymer and an ethene-co-l-octene (LLDPE(O)) copolymer. These copolymers present similar comonomer contents, molar mass, molar mass distribution and catalyst systems, but differ in their comonomer distribution. The blends were obtained through mechanical mixing using a single screw extruder at different compositions: 20, 40, 50, 60 and 80 wt.% of LLDPE. From DSC measurements two separated melting and crystallization peaks were observed and dynamic mechanical analysis showed two glass transitions indicating that LLDPE/t-PP blends are immiscible in amorphous and crystalline phases in the solid state. X-ray diffraction showed that the unit cell parameters of both polymers in the blends remain unchanged independent of the composition of the blend. (c) 2004 Elsevier Ltd. All rights reserved.41589490

Morphology and mechanical properties of blends of linear low density polyethylene and poly(ethenepropene-1-butene)

Blends of linear low density polyethylene (LLDPE) and ethene-propene-1-butene copolymer (t-PP) were obtained through mechanical mixing using a singlescrew extruder with different compositions: 20, 40, 50, 60, and 80 wt % of t-PP. For this, two types of polyethylene were used: 1-hexene comonomer and I-octene comonomer based. The same blends were prepared in a batch mixer and the torque and temperature were analyzed. The torque showed a decrease with increasing t-PP content, indicating better processability of the mixture in comparison with LLDPE. The morphology of the blends was analyzed by SEM and showed a composition dependence. The mechanical properties of the blends were evaluated by tensile tests. The results revealed that the best properties were obtained in a 20% t-PP blend. (c) 2006 Wiley Periodicals, Inc.10021255126

Polyhydroxybutyrate/acrylonitrile-g-(ethylene-co-propylene-co-diene)-g-styrene blends: Their morphology and thermal and mechanical behavior

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Polyhydroxybutyrate (PHB) is a biodegradable bacterial polyester emerging as a viable Substitute for synthetic, semicrystalline, nonbiodegradable polymers. An elastomer terpolymer of acrylonitrile-g-(ethylene-co-propylene-co-diene)-g-styrene (AES) was blended with PHB in a batch mixer and in a twin-screw extruder to improve the mechanical properties of PHB. The blends were characterized with differential scanning calorimetry, dynamic mechanical analysis, scanning electron microscopy, and impact resistance measurements. Despite the narrow processing window of PHB, blends with AES could be prepared via the melting of the mixture without significant degradation of PHB. The blends were immiscible and composed of four phases: poly(ethylene-co-propylene-co-diene), poly(styrene-co-acrylonitrile), amorphous PHB, and crystalline PHB. The crystallization of PHB in the blends was influenced by the AES content in different ways, depending on the processing conditions. A blend containing 30 wt %. AES presented impact resistance comparable to that of high-impact polystyrene, and the value was about 190% higher than that of pure PHB. (c) 2008 Wiley Periodicals, Inc.1102880889Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [01/07841-3

Aromatic/Aliphatic Polyester Blends

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Blends of poly(3-hydroxybutyrate) (PHB) and poly(ethylene terephthalate-co-1,4-cyclohexenedimethanol terephthalate) (PETG) were prepared in a batch mixer and in a twin screw extruder and characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), field emission scanning electron microscopy (FE SEM), flexural tests, biodegradation tests in soil compost and in an enzymatic medium. The torque data showed that the addition of PETG to PHB improved its processability. DSC, DMA and FE SEM showed that the polymers are immiscible with morphology dependent on the processing conditions. A fine dispersion of PETG in the PHB matrix was observed for extruded and injection molded blends. Flexural modulus for blends was higher for blends in comparison with PHB, while the impact resistance of blends containing 20 wt% and 30 wt% of PETG is comparable to the value for PHB. PHB is biodegradable, while PETG did not degrade either in simulated soil or in the alpha-amylase medium. On the other hand, the PHB phase of the blends degrades under these aging conditions. Thus, the addition of PETG to PHB results in advantage such as improving of processability and Young's modulus without significant changes in the impact resistance while keeping the biodegradability of PHB.183308317Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [Proc.: 01/07841-3, 00/10063-0, 2004/15084-6, 2003/09926-1, 04/13723-1